package myapps;

import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.common.utils.Bytes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.Topology;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.Materialized;
import org.apache.kafka.streams.kstream.Produced;
import org.apache.kafka.streams.state.KeyValueStore;

import java.util.Arrays;
import java.util.Locale;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;

public class WordCount {
    public static void main(String[] args) throws Exception {
        Properties props = new Properties();
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "streams-wordcount");
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
        props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass());

        final StreamsBuilder builder = new StreamsBuilder();

        KStream<String, String> source = builder.stream("streams-plaintext-input");

        // KTable<String, Long> counts =
        //         source.flatMapValues((ValueMapper<String, Iterable<String>>) value -> Arrays.asList(value.toLowerCase(Locale.getDefault()).split("\\W+")))
        //                 .groupBy((key, value) -> value)
        //                 // Materialize the result into a KeyValueStore named "counts-store".
        //                 // The Materialized store is always of type <Bytes, byte[]> as this is the format of the inner most store.
        //                 .count(Materialized.<String, Long, KeyValueStore<Bytes, byte[]>> as("counts-store"));
        // counts.toStream().to("streams-wordcount-output", Produced.with(Serdes.String(), Serdes.Long()));

        // 上面的方法可以简化为：
        source.flatMapValues(value -> Arrays.asList(value.toLowerCase(Locale.getDefault()).split("\\W+")))
                .groupBy((key, value) -> value)
                .count(Materialized.<String, Long, KeyValueStore<Bytes, byte[]>>as("counts-store"))
                .toStream()
                .to("streams-wordcount-output", Produced.with(Serdes.String(), Serdes.Long()));

        final Topology topology = builder.build();
        final KafkaStreams streams = new KafkaStreams(topology, props);
        final CountDownLatch latch = new CountDownLatch(1);

        // attach shutdown handler to catch control-c
        Runtime.getRuntime().addShutdownHook(new Thread("streams-shutdown-hook") {
            @Override
            public void run() {
                streams.close();
                latch.countDown();
            }
        });

        try {
            streams.start();
            latch.await();
        } catch (Throwable e) {
            System.exit(1);
        }
        System.exit(0);
    }
}
